State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070 Republic of China.
2Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, 305-764 Republic of Korea.
Commun Biol. 2019 Apr 29;2:151. doi: 10.1038/s42003-019-0414-6. eCollection 2019.
The intracellular K level in bacteria is strictly controlled by K uptake and efflux systems. Among these, KdpFABC is a high-affinity K transporter system that is generally activated by the KdpDE two-component system in response to K limitation stress. However, the regulatory mechanism remains obscure in bacteria lacking the genes. Here we report that the transcription of a operon is distinctively regulated by a cyclic diadenylate monophosphate (c-di-AMP) riboswitch located at the 5'-untranslated region of transcript, and binding of c-di-AMP to the riboswitch promotes its intrinsic termination that blocks the transcription. Further, the intracellular c-di-AMP concentration was found to decrease under the K limitation stress, leading to transcriptional read-through over the terminator to allow expression. This regulatory element is found predominantly in the group and correlate well with the K and c-di-AMP homeostasis that affects a variety of crucial cellular functions.
细菌细胞内的 K 水平受到 K 摄取和外排系统的严格控制。其中，KdpFABC 是一种高亲和力的 K 转运系统，通常由 KdpDE 双组分系统激活，以响应 K 限制应激。然而，在缺乏 基因的细菌中，其调控机制仍不清楚。在这里，我们报告说，一个 操纵子的转录受到位于 转录物 5'非翻译区的环二腺苷酸（c-di-AMP）核糖开关的显著调控，c-di-AMP 与核糖开关的结合促进其内在终止，从而阻止 转录。此外，发现在 K 限制应激下，细胞内的 c-di-AMP 浓度降低，导致终止子上的转录通读，从而允许 表达。这个调节元件主要存在于 组中，与 K 和 c-di-AMP 的动态平衡密切相关，影响着各种关键的细胞功能。
